Data from: Non-linear effect of sea ice: Spectacled Eider survival declines at both extremes of the ice spectrum
Christie, Katherine S., Alaska SeaLife Center
Hollmen, Tuula E., University of Alaska Fairbanks, Alaska SeaLife Center
Flint, Paul, United States Geological Survey
Douglas, David, United States Geological Survey
Published Nov 20, 2018 on Dryad.
Cite this dataset
Christie, Katherine S.; Hollmen, Tuula E.; Flint, Paul; Douglas, David (2018). Data from: Non-linear effect of sea ice: Spectacled Eider survival declines at both extremes of the ice spectrum [Dataset]. Dryad. https://doi.org/10.5061/dryad.s1c5m5k
Understanding the relationship between environmental factors and vital rates is an important step in predicting a species’ response to environmental change. Species associated with sea ice are of particular concern because sea ice is projected to decrease rapidly in polar environments with continued levels of greenhouse gas emissions. The relationship between sea ice and the vital rates of the Spectacled Eider, a threatened species that breeds in Alaska and Russia and winters in the Bering Sea, appears to be complex. While severe ice can impede foraging for benthic prey, ice also suppresses wave action and provides a platform on which eiders roost, thereby reducing thermoregulation costs. We analyzed a 23-year mark-recapture dataset for Spectacled Eiders nesting on Kigigak Island in western Alaska, and tested survival models containing different ice and weather-related covariates. We found that much of the variation in eider survival could be explained by the number of days per year with >95% sea ice concentration at the Bering Sea core wintering area. Furthermore, the data supported a quadratic relationship with sea ice rather than a linear one, indicating that intermediate sea ice concentrations were optimal for survival. We then used matrix population models to project population trajectories using General Circulation Model (GCM) outputs of daily sea ice cover. GCMs projected reduced sea ice at the wintering area by year 2100 under a moderated emissions scenario (RCP 4.5) and nearly ice-free conditions under an unabated emissions scenario (RCP 8.5). Under RCP 4.5, stochastic models projected an increase in population size until 2069 coincident with moderate ice conditions, followed by a decline in population size as ice conditions shifted from intermediate to mostly ice-free. Under RCP 8.5, eider abundance increased until 2040 and then decreased to near extirpation toward the end of the century as the Bering Sea became ice-free.
Projected sea ice data (number of days with >95% sea ice cover and <15% sea ice cover) for the Spectacled Eider core wintering area. Data from Global Circulation Models were downloaded from archives of CMIP5 GCM outputs (see Table S3 for a list of models).
Historical sea ice data
This file contains observed sea ice concentrations extracted for the core SPEI wintering area from daily gridded (25 km resolution) estimates that were derived from passive microwave satellite imagery using the Bootstrap Algorithm and disseminated by the National Snow and Ice Data Center, Boulder, CO. Data Citations: (1) Comiso, J. C. 2017. Bootstrap Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I-SSMIS, Version 3. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi: https://doi.org/10.5067/7Q8HCCWS4I0R. (2) Cavalieri, D. J., C. L. Parkinson, P. Gloersen, and H. J. Zwally. 1996, updated yearly. Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I-SSMIS Passive Microwave Data, Version 1. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi: https://doi.org/10.5067/8GQ8LZQVL0VL.
SPEI encounter histories
The data file contains encounter histories for Spectacled Eiders captured on Kigigak Island, Alaska from 1992-2015.